1. Field of the Invention
The present invention relates to an apparatus for cooling particulate materials and, more particularly, to a mass flow cooler wherein particulate material is fed into a vertical bin through an inlet near the top thereof, descends uniformly by force of gravity past a plurality of vertical cooling elements, and is controllably discharged from the bottom of the cooler.
2. Description of Related Art
The production of certain particulate materials, such as potash and phosphates, requires that the materials be cooled to, for example, avoid caking. Mass flow coolers have been developed to reduce energy and maintenance costs as well as avoid the attrition and abrasion problems experienced with rotating drum or fluidized bed cooling devices. These mass flow coolers typically comprise a vertical housing or bin with an opening at the top through which the material to be cooled is introduced, one or more heat exchanger elements for cooling the material and a discharge hopper at the bottom of the bin to control the flow of the material through the bin. Such a cooler is disclosed in U.S. Pat. No. 4,546,821 issued to Kummel. The problem with Kummel, however, is that the design of the heat exchanger element may interfere with the flow of material through the bin and yet not provide for uniform cooling of the material. In addition, the discharge mechanism may not promote the effective mass flow of material through the bin. Another embodiment of a mass flow cooler, disclosed in European Patent Application number 90302189.7, utilizes a multiplicity of parallel, spaced, vertical heat exchanger plates to cool the material. These plates interfere with the lateral flow of material through the bin and are relatively difficult to manufacture and incorporate into the cooler. In addition, the flow channels within the plates and the rest of the cooler define a closed system for the cooling fluid which could result in a dangerous pressure buildup should the flow of fluid stop. Furthermore, the amount of material being discharged from the bin should not be greater than the amount of material being fed into the bin to ensure that the material completely fills the bin so that cooling is uniform and cooling efficiency can be maintained at all times.